female beetles have a thirst for sex
TRANSCRIPT
In brief–
with antiviral drugs such as
Tamiflu, says Cameron Simmons
at the Hospital for Tropical
Diseases in Ho Chi Minh City,
Vietnam, who led the study.
However, antibodies may be
costly and hard to mass-produce,
meaning their greatest benefit
may be treating the few people
who catch the disease directly
from birds, and to contain local
outbreaks. “This is not a tool for
public-health-level control of
H5N1,” says Simmons. The
antibodies may also not be
effective if the virus mutates.
H5N1 survived, compared with
none of the five mice not given
antibodies. They also worked as a
preventive therapy when given
before the mice were infected
(PLoS Medicine, DOI: 10.1371/
journal.pmed.0040178).
“If it works after three days,
that’s very good news,” says Albert
Osterhaus, a bird flu expert at
Erasmus University in Rotterdam,
the Netherlands, who was not
involved in the study. “It means
you could use it after the first
symptoms.” The antibody
treatment could be combined
PLANTS send out SOS signals
when they are under attack.
If insects are feeding on them,
some plants emit volatile
chemicals that attract enemies
of the insects. What is surprising,
though, is that neighbouring
plants not being eaten also send
out distress signals to call in
these “bodyguards”.
Why so-called secondary
signallers do it has been a mystery,
but now Yutaka Kobayashi and
Norio Yamamura of Kyoto
University, Japan, think they
have solved it.
The answer is family values,
or in evolutionary parlance, kin
selection. “My hypothesis views
secondary signallers as crying for
help to save their family,” says
Kobayashi. The pair used an
evolutionary model to show that
if the cost of making the SOS
signal was low and there was a
high likelihood of having relatives
growing nearby – both conditions
which are often true in real life –
then secondary signalling would
evolve (Evolutionary Ecology,
DOI: 10.1007/s10682-007-9165-9).
“Neighbouring undamaged
plants emit the secondary signal
probably to help the damaged
plants,” says Kobayashi.
Plants call guards
to protect family
BUYING a lady a drink to win her
favour is a trick not confined to men.
Some beetle females will mate simply
to quench their thirst.
The bean weevil Callosobruchus maculatus feeds on dry pulses. With
a diet like this, the male’s ejaculate is
a valuable water source for females.
Martin Edvardsson at Uppsala
University, Sweden, tested the idea
that females tap into this by keeping
them on dry beans with or without
access to water. Females living on
beans alone accepted more matings,
presumably to secure the water in the
seminal fluid (Animal Behaviour, DOI:
10.1016/j.anbehav.2006.07.018).
Edvardsson says that the energy
used to produce the ejaculate, which
makes up a whopping 10 per cent of
a male’s weight, is well spent. Once
impregnated, females lose interest in
sex – probably to avoid further injury
from the male’s spiny penis. They are
more likely to mate again if they are
thirsty. “This is a massive investment
for the male,” Edvardsson says. “It
buys them time before the females
remate and their sperm have to
compete with that of other males.”
Females with access to water lived
on average for a day and a half longer
than those without water. Since
average lifespan is only around nine
days, this makes quite a difference to
the total number of eggs they can lay.
ALTHOUGH they can only babble,
babies seem to have a keen eye for
speech: they can distinguish
between different languages simply
by reading your lips.
Whitney Weikum and colleagues
from the University of British
Columbia in Vancouver, Canada,
showed babies videos of talking
adults, with the sound turned off.
Babies soon got bored of the silent
clips, but they watched with
renewed interest when speakers
switched from English to French
(Science, vol 316, p 1159).
This ability lasted only until the
age of about 8 months – unless
the babies came from bilingual
households, when it continued. This
suggests that visual cues may help
babies avoid mixing up different
languages, says Weikum. “It supports
the idea that infants come prepared
to learn multiple languages and are
thus equipped to discriminate them
auditorily and visually,” she says.
Although there is no direct
evidence that visual cues help
children to learn a language, “it does
suggest that in language learning,
the brain may not be tied to speech
per se”, says Laura-Ann Petitto, a
language development researcher at
Dartmouth College in Hanover, New
Hampshire. She previously showed
that deaf babies use visual cues to
learn sign language, but “never did
we dream that young hearing babies
acquiring spoken languages also use
visual cues in this stunning way”.
AT FIRST the two Vietnamese
adults had nothing in common
but the good fortune to survive
a brush with H5N1 bird flu. Now
they share something else: their
immortalised blood cells may
help stop bird flu from becoming
a global pandemic.
Antibodies made from the
pair’s blood cells have cured
mice infected with the H5N1
virus, suggesting they might
make an effective treatment or
preventive therapy for humans.
All 20 mice given the antibodies
three days after infection with
PUNC
HSTO
CK
ANDR
EW SY
RED/
SHEF
FIEL
D UN
IVER
SITY
/SPL
Blood of bird flu survivors gives promising antibodies
20 | NewScientist | 2 June 2007 www.newscientist.com
They’re watching your language
Female beetles have a thirst for sex
070602_N_InBrief.indd 20070602_N_InBrief.indd 20 25/5/07 4:29:49 pm25/5/07 4:29:49 pm